Can you use an on screen keyboard on iOS?

Hi there I apologize if this is something most people know but I can’t find any info about it at all on google. I am trying to play some old GTA on mobile, specifically Vice City and San Andreas, and as you may know they’re pretty hard without cheats, especially on mobile. I want to use some cheat codes but you need to put them in with a keyboard, and I can’t for the life of my figure out how to do it on iOS. Can you even? Thanks for any help.